STEP 1: MARINADE BEEF
Put the beef into a medium bowl, add the marinade ingredients and 4 tablespoons water and mix well. Cover and chill for at least 4 hours.

STEP 2: STIR FRY VEGETABLES
Heat 1 tablespoon oil in a wok or a large frying pan with high sides over a high heat. Add the onions and stir-fry until they have softened slightly. Add the green pepper, sprinkle in 1 tablespoon water and stir-fry until the peppers are cooked but still crunchy. Remove the onions and red pepper and set aside.

STEP 3: FRY EVERYTHING TOGETHER IN A WOK
Reheat the wok over a high heat. Add 1½ tablespoons oil and the cracked peppercorns and fry for 15 seconds. Add the ginger and garlic, fry until fragrant, then spread the marinated beef slices over the base of the wok in a single layer. Allow to develop a golden crust on the bottom and then flip every 30 seconds for a further 2 minutes, or until the beef slices have a golden crust all over. Return the onions and red pepper to the wok, add the oyster sauce and toss to coat.

STEP 4: FINISH AND SERVE
Reduce the heat to low, mix the corn flour and 3 tablespoons water into a slurry then stir it into the wok. Increase the heat and toss everything until the sauce is translucent. Serve with steamed rice.